Goes through gears when turning key

[Norway450 0]

P1799 Actual position of turning angle sensor

P2408 Transmission: Incremental sensor

 

 

[tolsen 630]

Some disagreement between the two sensors. 

Check wiring again using my method. 

 

Remove and check smoothness of shift drum turning angle sensor using a multimeter set to read Ohms. 

[Norway450 0]

I'll check them again, and also the circuitry connected to the angle sensor (ADC).

The angle sensor is new, and smooth.

 

[Norway450 0]

I connected a oscilloscope directly to the inputs of the gear sensor on the ECU, see video below.

First I turn the key, and it goes up the gears and back to neutral. Then I drive until I reach 6th gear.

 

 

The voltages seems stable, sane and correspond to the current gear.

They also agree with the raw sensor values read from "1721 Raw value B43 (Gear position sensor)".

R: 4765 mV

N: 4384 mV

1: 4018 mV

2: 3426 mV

 

However, the values read from "18161 Value of turning angle sensor" seem to not correspond.

R: 207

N: 129

1: 54

2: 232 (sudden jump in the opposite direction? 8bit wrap-around?)

 

Can someone please post their values from these 2 monitors at each gear position so I can compare?

 

Also, a gear teach in ends with an error.

 

Summary: Sensor, wires and analog to digital converter seems to work, numbers are being garbled in the ECU program.
 

 

 

 

 

Edited June 11, 2019 by Norway450

[cregi 1]

On 3/4/2019 at 11:18 PM, Norway450 said:

Hi, Rolf from Norway here, I have a 2001 City-coupe.

 

Gear box goes to 6th gear and back to N when turning the key.

Usually I can then drive it without any problems, but sometimes one of two tings happen (usually in the morning):

1: It will not go into 1 or R, just making rythmic clunking noises. I have confirmed this to be the clutch servo not opening the clutch enough.

2: it will go in gear, but as soon as I press the throttle the car lurches forward.

I have cleaned and checked the angle sensor, clutch servo, gear change servo and wires.

Also checked the brain box next to the air filter for water ingress.

 

I think the root cause is that the gearbox electronis does not know which gear it is in, and then goes end to end to find out. I can see the voltage drop as the gear servo hits both ends.

Therefore I have ordered a new gear angle sensor.

 

Any tips?

 

 

 

Hi, 

Could you finally find the problem caussing this issue?

I am getting a similar problem in a 2003 Smart Roadster , when I turn the key to ON the gearbox goes from 6th to 1st and then N, and then I can start the car as usually.

Also sometimes when changing a gear, I get the 3 lines in the speedo, and the car stays in N or clucth dissengaged. The 3 lines dissapear once I stop and restart the car , and the car runs good again. 

 

Thanks in advance for any info.

 

 

[Willys 741]

Have you checked your wiring where it goes over the inter cooler scoop area as that is a typical spot for the wires to get rubbed through? Then check all connections for green fuzzies etc.....have you checked all your grounding pins for same corrosion issues? Take the gear selector motor off and see whats inside, again looking for corrosion and or rust. Have you checked your clutch adjuster or actuator for typical issues.??   Do you have a STAR or know someone who does? A STAR will cost you far less than a few trips to a garage who doesn't know what they're looking for.  imho.  It will also be able to reteach or introduce a new ECU to speak to the speedo and SAM because if they do not know each other the car will not run etc.    

I haven't seen anyone do what 450 has done with his osiliscope etc  as most owners wouldn't own one or know how to use it....?  

Let us know what you have done so far  etc etc....the 3 bars of death on the speedo indicate limp mode or worse.  Have you read any codes, are there any idiot lights showing on the speedo?  Just obvious stuff to start with...?

[cregi 1]

On 17/11/2023 at 6:05 PM, Willys said:

Have you checked your wiring where it goes over the inter cooler scoop area as that is a typical spot for the wires to get rubbed through? Then check all connections for green fuzzies etc.....have you checked all your grounding pins for same corrosion issues? Take the gear selector motor off and see whats inside, again looking for corrosion and or rust. Have you checked your clutch adjuster or actuator for typical issues.??   Do you have a STAR or know someone who does? A STAR will cost you far less than a few trips to a garage who doesn't know what they're looking for.  imho.  It will also be able to reteach or introduce a new ECU to speak to the speedo and SAM because if they do not know each other the car will not run etc.    

I haven't seen anyone do what 450 has done with his osiliscope etc  as most owners wouldn't own one or know how to use it....?  

Let us know what you have done so far  etc etc....the 3 bars of death on the speedo indicate limp mode or worse.  Have you read any codes, are there any idiot lights showing on the speedo?  Just obvious stuff to start with...?

 

Hi Willys, thanks for the asnwer.

Yes I have already checked the gear box wiring, the connectors and the ground points next to the wheel arc and the one that goes to the gear box. All looks apparently fine.

Regarding the actuator, firstly I lubbed it and made the actuator clutch adjustment the with the Star of a colleague, the problem still came randomly after it. Then I changed the actuator by other used one, and for 3 or 4 weeks it looked better, no errors and smooth and faster shifts, but finally suddenly the 3 lines came again. And as usually re-starting the engine solved momentarily the problem. And from time to time when turning the key the car goes through all gears.  Checked also the clutch fork and no holes on it.

 

My next steps is going to change the gear box fluid, and after that to check or change the gear sensor and/or  the gear selector motor.

 

I need to meet again my coleague to read the error codes with the Star, so far I only could read it with a cheap ELM obd reader that shows the error "P0702 , Estatus. Temporal, Transmission control system - electrical "

 

 

 

 

 

 

[Willys 741]

4 hours ago, cregi said:

 

Hi Willys, thanks for the asnwer.

Yes I have already checked the gear box wiring, the connectors and the ground points next to the wheel arc and the one that goes to the gear box. All looks apparently fine.

Regarding the actuator, firstly I lubbed it and made the actuator clutch adjustment the with the Star of a colleague, the problem still came randomly after it. Then I changed the actuator by other used one, and for 3 or 4 weeks it looked better, no errors and smooth and faster shifts, but finally suddenly the 3 lines came again. And as usually re-starting the engine solved momentarily the problem. And from time to time when turning the key the car goes through all gears.  Checked also the clutch fork and no holes on it.

 

My next steps is going to change the gear box fluid, and after that to check or change the gear sensor and/or  the gear selector motor.

 

I need to meet again my coleague to read the error codes with the Star, so far I only could read it with a cheap ELM obd reader that shows the error "P0702 , Estatus. Temporal, Transmission control system - electrical "

 

 

 

 

 

 

OK you have the use of a STAR, great, you can re-teach the transmission gear selector gear location points. IF the issue semi resolved itself after changing the actuator, perhaps it's in the actuator wiring that is causing your issues? Check the contenuity of the plug connection to make sure there is no break or weak connection in the actual plug and the wiring that leads up to it. Check for a pin that may be pushed back within the plug? 
OK, when you checked the ground points did you take the nut off and check for corrosion between the eyelets of each ground wire? Yes they may look good at a glance so to speak but these cars are very prone to get bad grounds.  There should be a ground point as you look into the engine bay just under the front lip of the engine bay cover at the 11 o'clock position, it sometimes has issues. Then the main ground strap that is a braided type wire, it usually simply disintergrates.   I would also take the gear select motor off and open it up also if you haven't already and see how good or bad it is inside. I have seen one so badly corroded from rust and dirt it was simply junk.
As for the transmission oil, always a good idea to change fluids from time to time. I have rebuilt my own transmission just because I'm curious....it has a very slight discolouration or smeer of dirt in the case which easily flushed with parts cleaner as I had it apart. This amount of dirt or debris wouldn't do anything to the operation of the transmission imho at all. The car had 120,000kms on it when I did all of this work.
Let us know how you make out.

[cregi 1]

18 hours ago, Willys said:

OK you have the use of a STAR, great, you can re-teach the transmission gear selector gear location points. IF the issue semi resolved itself after changing the actuator, perhaps it's in the actuator wiring that is causing your issues? 

Yes it could be the actuator wiring or any other of the wirings because at the same time i was checking all the wires and cleaning all the connectors that goes to the gear box. 

Do you know if the Star may give a more accurate error, to know if it is related with the actuator, selector motor , or gear sensor? Or just gives an ambiguos error like the P0702 Transmission control system - electrical ?

 

19 hours ago, Willys said:

OK, when you checked the ground points did you take the nut off and check for corrosion between the eyelets of each ground wire? Yes they may look good at a glance so to speak but these cars are very prone to get bad grounds.  There should be a ground point as you look into the engine bay just under the front lip of the engine bay cover at the 11 o'clock position, it sometimes has issues. Then the main ground strap that is a braided type wire, it usually simply disintergrates.  

I took the nut off and checked the eyelet (on the roadster there is only one eyelet on that earth point where all the earth wires are crimped ), checked that all wires were strongly attached to the eyelet and cleaned with a sand paper and conatct cleaner spray both the eyelet and the chassis bolt. If I am not wrong on the engine bay the Roadster has an earth point next to the right rear wheel arc and the air box filter and the main ground braided strap that goes to the gear box. I added a ground cable of 25mm2 section on this main ground point , just to help the braided strap.

 

19 hours ago, Willys said:

I would also take the gear select motor off and open it up also if you haven't already and see how good or bad it is inside.

How difficult is this? Aree the bolts accesible? 

 

In other hand, I read that the car can run without the gear positition sensor , because it is only used when you do a gear position re-teach, normally te eECU uses the encoder built in the selector motor to know the selector position. But, do you know if from time to time the ECU cross check the information of both sensors? Or it is strictly only used when you re-tech with the Star? 

 

Thanks a lot for the help 

 

[Willys 741]

The gear position sensor counts revolutions of the gear selector motor, no? It gives this information to the ECU constantly I would expect and IF the gear selector motor doesn't go to the correct number of revolutions it causes an error code, no?  It's just how I would expect it to work but could be wrong..?  Getting at the gear select motor isn't an easy job if I remember correctly as mine is under inter cooler scoop arrangement...which means taking off the inter cooler etc etc which is a mentally painful job.....I haven't had to do this in a long while so my memory could be wrong. Either way if you are curious to see if the motor has corrosion inside you have no other choice, do you...?  It is just a motor after all so it isn't that difficult once you get it off and on a bench to check it. 
All of my experience is on a CDI 450 2005-2006  so things will be slightly different but the basics should be the same no?

The STAR is a dealership diagnostic tool that reads the codes and also tells you how to repair the issue, the hard part is understanding how to get to the appropriate area within the STAR program etc. I use mine so infrequently that I forget how to get where I need to go compared to a mechanic who uses it daily, which makes it painful to deal with it. BUT, nothing else gives you the information like a STAR. It has colour pics showing what you are after, what tools to use, how to fix it, and how to test everything and what readings you need to see to repair things.   After saying all this it is difficult for someone to follow who doesn't have mechanical knowledge of some degree, but if you can learn then it is very very useful and worth the money to get one.  Ask other people who own one and get more opinions on it .......but I haven't heard anyone be able to use more modern testers/readers better than the STAR system.  Yes some can do many things but still can't do it all. You can buy very very expensive reader/scan tools etc but they also give so much information that it requires mechanical experience to know what you are looking at.   I just had one of my cars plugged into an $11,000 scan tool and it showed all sorts of stuff I knew nothing about which simply confused me but my mechanic knew what it all was.....still didn't resolve my problem...!

[cregi 1]

On 21/11/2023 at 4:04 PM, Willys said:

The gear position sensor counts revolutions of the gear selector motor, no? It gives this information to the ECU constantly I would expect and IF the gear selector motor doesn't go to the correct number of revolutions it causes an error code, no?  It's just how I would expect it to work but could be wrong..?  Getting at the gear select motor isn't an easy job if I remember correctly as mine is under inter cooler scoop arrangement...which means taking off the inter cooler etc etc which is a mentally painful job.....I haven't had to do this in a long while so my memory could be wrong. Either way if you are curious to see if the motor has corrosion inside you have no other choice, do you...?  It is just a motor after all so it isn't that difficult once you get it off and on a bench to check it. 
All of my experience is on a CDI 450 2005-2006  so things will be slightly different but the basics should be the same no?

The STAR is a dealership diagnostic tool that reads the codes and also tells you how to repair the issue, the hard part is understanding how to get to the appropriate area within the STAR program etc. I use mine so infrequently that I forget how to get where I need to go compared to a mechanic who uses it daily, which makes it painful to deal with it. BUT, nothing else gives you the information like a STAR. It has colour pics showing what you are after, what tools to use, how to fix it, and how to test everything and what readings you need to see to repair things.   After saying all this it is difficult for someone to follow who doesn't have mechanical knowledge of some degree, but if you can learn then it is very very useful and worth the money to get one.  Ask other people who own one and get more opinions on it .......but I haven't heard anyone be able to use more modern testers/readers better than the STAR system.  Yes some can do many things but still can't do it all. You can buy very very expensive reader/scan tools etc but they also give so much information that it requires mechanical experience to know what you are looking at.   I just had one of my cars plugged into an $11,000 scan tool and it showed all sorts of stuff I knew nothing about which simply confused me but my mechanic knew what it all was.....still didn't resolve my problem...!

 

No, the gear position sensor reads the position of the gear selector , this is the small round shapped  sensor fitted in one side of the gear box. And I read that it is only used when you do a retaught of the gear position with the Star, but you can disconnect it and drive the car without the sensor normally, at least for a short time (I don´t know if from time to time the ECU reads it to crosschek the information given by the gear selector motor encoder).   In other hand the gear selector motor has its own encoder built-in inside, this is the one that gives the information to the ECU during normal operation. 

 

 

[Willys 741]

OK....